In the United States and throughout the world, the multiple use of hypodermic syringe products which are intended for single use only is instrumental in drug abuse and more particularly in the transfer of contagious diseases. Such contagious diseases include AIDS and hepatitis. The transfer is most prevalent in intravenous drug users who routinely share and reuse syringes, but can also be a problem for the medical community if proper precautions to prevent multiple use of disposable syringes are not followed. Furthermore, the effects of multiple use are a major concern in third world countries where repeated use of syringe products may also be responsible for the spread of many diseases.
Many attempts have been made to remedy this problem. Some early attempted solutions involved destruction of the syringe after use either by using a destructive device or providing a syringe assembly with frangible zones so that the syringe could be rendered inoperable by the application of force. Although many of these devices work quite well, they require the specific intent of the user followed by the actual act to destroy or render the syringe inoperable. None of these devices is effective with a user having the specific intent to reuse the syringe.
Accordingly, there is a need for a non-reuseable syringe which becomes inoperative or incapable of further use automatically without an additional act on the part of the user. Co-owned U.S. Pat. No. 5,215,524, issued Jun. 1, 1993, the contents of which are hereby incorporated by reference, discloses a single use syringe which utilizes a disconnecting plunger stem. This syringe becomes inoperative automatically after a single use.
However, the need for a non-reusable syringe must be met without preventing the filling or use of the syringe under normal conditions. One such use under normal conditions includes the ability to aspirate fluid using the syringe. It is common in the medical community to aspirate fluid during the use of a syringe (i.e., to alternately retract and extend the plunger of the syringe without expelling all contents of the syringe). This ability to aspirate must still be available with a single use syringe, and is not available with the syringe of U.S. Pat. No. 5,215,524.
Although various types of single use non-reuseable syringes have been proposed, the severity of the AIDS epidemic and the need for solutions to the above problems continuously provide a need for other types of non-reuseable syringes, particularly those which also provide for aspiration.